It is well known that the montmorillonite group of clays hydrate and swell in fresh water but the swelling is substantially inhibited in salt contaminated water. Salt contaminated water is often encountered in the environments of use of bentonite clays where bentonite is advantageously employed for its swelling capacity, for example, as an additive in drilling muds for the purpose of sealing fissures in earthen formations surrounding the drill hole to prevent loss of drilling fluid; and in the sealing of lagoons and landfills. When contacted with salt contaminated water, the swelling capacity and stability of common montmorillonite clays is severely inhibited making it necessary to use much greater quantities of the clay to achieve the degree of swelling needed for sealing purposes. In some cases the palygorskite clays are used instead of the montmorillonite clays because of their better dispersing properties in salt water, as disclosed in U.S. Pat. No. 4,202,413.
In the past, modified bentonite clays have been developed by this assignee having a swelling capacity substantially uninhibited in salt water. Examples of such modified bentonites are the polymer treated bentonites disclosed in the Clem U.S. Pat. Nos. 3,949,560, 4,021,402, 4,048,373 and 4,103,499.
The present invention is directed to montmorillonite clay compositions including gum additives capable of permitting water swellable montmorillonite clays to seal against permeability in earthen formations when used in drilling fluids and for water sealing in lagoons and landfills when contacted by salt water. Others have added various gums to bentonite compositions for achieving desired viscosities, as disclosed in the following patents, but none of these patents discloses applicant's composition and none teaches that the composition disclosed herein permits montmorillonite clays to remain stable without component separation when used in a salt water environment: Harris U.S. Pat. No. 1,498,269; Wallace U.S. Pat. Nos. 1,955,936 and 2,287,183; Berg U.S. Pat. No. 2,260,882; Parsons U.S. Pat No. 2,294,012; Jeanneret U.S. Pat. No. 3,275,460; Gropis U.S. Pat. No. 3,909,421; Brewer U.S. Pat. No. 3,921,581; Piunguian U.S. Pat. No. 3,989,534; and Messenger U.S. Pat. No. 4,202,413.